Small-aspect-ratio wing



Dec. 8, 1936. s. P. NEMETH 2,063,456

SMALL ASPECT RATIO WING Filed Dec. l5, 1935 'IETUL Patented Dec.- 8, 1936 UNITED STATES PATENT oFFlcE 6 Claims. This invention relates v'tofa circular airplane y wing. Such wings'have the advantages of being free from spinning tendencies, stall proof, and

c'ompact in design. The circular wings so far proposed have however so small a ratio of the lift divided by the drag, at small angles of attack, as to make them impractical.

An analysis of the measured air forces of small.- aspect-ratio wings shows now that said low value of the lift divided by the drag is not solely and principally the consequence of a comparatively large drag, as would naturally suggest itself, but it is also and to a dominant extent the consequence of a comparatively small lift. That is to say: at small angles of attack corresponding to cruising speeds, the lift is even smaller than could ordinarily be expected from the experience with large-aspect-ratio wings, allowing fully for the iniiuence of the small aspect ratio as predicted by the ordinarily accepted wing theory. The restrictions of aerodynamic theory do not stand in the way of a larger lift under the same ilight conditions. The present invention provides for a small-aspect-ratio wing havingla lift larger than that of ordinary small-aspect-ratio wings, approaching the lift `predicted by theory.

The relation between the magnitude of the lift and the angle of attack of ordinary wings of different aspect ratios is well illustrated in the diagrams on page of Report No. 431 of the National Advisory Committee for Aeronautics, entitled Characteristics of ClarkYAirfoils of Small Aspect Ratios, by C. H. Zimmermann. The solid curve in gure 2 on that page is practically straight in the region of small angles of attack, indicating thereby that the rate of change of the lift in relation to the angle of attack is constant. That curve relates to an aspect ratioof 6. The corresponding curves referring to small aspect ratios are however bent up. The rate of lift increase is thereby indicated to be deiicient at small angles of attack. My inventionprovides for a smallaspect-ratio wing with a nearly `constant rate of lift increase at small angles of attack.

My invention resides in the discovery that a wing with circular planiform, notwithstanding its small aspect ratio, creates a full lift, and one proportional to the angle of attack, if composed of at least two portions, a major front portion, and a minor rear portion, said rear portion being vertically staggered with respect to the front portion so that the leading edge of the rear portion is positioned below the trailing edge of the front portion, and separated therefrom by an open gap. My invention provides accordingly for a circular compound wing characterized by a substantially straight lift curve -as contradistinguished from a sagging lift curve.

Such compound circular wing would in addition naturally possess all advantages owing from that arrangement for all wings, whatever their aspect ratio may be. The arrangement lends itself easily for using the outer portions of the rear wing portion as ailerons, and the center portion as a iiap, so that at large angles of attack the latter may be turned dow-n about a transverse axis intov contact with the front wing portion, and the burbling of amelioration by my novel arrangement not urgent'.

LThe adoption of my circular wing structure is however not predicated on the experience with large-aspect-rati'o wings because with them there 'is no opportunity for the principal useful eiect of my arrangement, namely to make the lift proportional to 'the angle of attack, whereby a large efflciency of a small-aspect-ratio Awing is obtained, because largeFaspect-ratio wings create a lift proportional to the angle of attack anyhow, even without'dividing them up in the characterized manner.

These and other desirable objects and advantages of my invention will be illustrated in the accompanying drawing and described in the specilication, a certain preferred embodiment being disclosed by way of illustration only; for, since the underlying principles may be incorporated in other speciiic devices, it is not intended to be limited to the one here shown except as such limitations ,are clearly imposed by the appended claims.

In the drawing like numerals refer to similar parts throughout the several views, of which Fig. 1 represents a vertical cross section through the center of a wing incorporating my invention, on line I-l of Figure 2,

Fig. 2 represents a plan view of the same wing as seen from above, and

Fig. 3 represents in a schematical diagram the control system of the several rear portions of the wing.

The wing is composed of a front portion I and rear portions 2, 3, and 4. The outer edges of all four portions i to I, seen from above, form a circle 5, 6, 1, 8. The trailing edge 9 of front wing 'portion l is a regularly rounded arc convex to the rear, and has practically the same shape as the leading edges I I, I2 of the rear wing portions,

' the best results by using streamlined double cambered wing sections, the upper camber line,

like 23 having a larger curvature than the lower A camber line, like 24, with moderate roundness oi the leading. edges 5, II, and I2, which are almost sharp, and with sharp trailing edges 6 to 9, the maximum chord oi the iront portion I being three quarters of the span.

Front wing portion I is rigidly secured to the airplane structure in any suitable manner, for instance by being provided with a front spar I4 and a rear spar I5, said spars being held by'and rigidly secured to struts I6 of the airplane fuselage not shown in the drawing.

Extending backward from the rear spar I are provided arms I1, bent down behind the front Wing portion and having at their ends hinges I8 behind and below the trailing edge 9 of the front wing portion. The rear wing portions are hinged at I8 to these arms I'I, the axes oi rotation extending approximately vparallel to the average direction of theportion of the trailing edge 9 in front of the rear portion supported. In their normal flying position, the rear portions 2, 3 and 4 are substantially parallel to the front portion I of the wing, and are separated therefrom by the gap I9 extending all along the rear of the front portion and the front of the rear portions of the wing. Trailing edge 9 is disposed substantially on top of and above leading edges II and I2. It is separated therefrom by a gap I9 extending all along the rear of the front portion and the front of the rear portions of the wing. I obtained good results by making gap I9 approximately equal to one thirty second of the wing span.

The outer rear portions 2 and 4 may be turned as ailerons by means of the control stick 20 to which they are connected by means of the control cables 2I in any suitable manner, for instance as diagrammatically indicated in Figure 3. The rear center portion 3 is connected by similar control cables to an auxiliary hand lever 22 secured against motion while not in use. Turning hand lever 22 turns ilap 3 into the position shown in dashed line in Figure l. In its extreme position, its leading edge I2 is in close vicinity to iront wing portion I and the gap I 9 becomes then very narrow.

This latter is the position of the iiap during starting and landing. For cruising, the hand lever 22 is placed so as to move flap 3 into the position shown in solid line in Figure 1. During all conditions of iiight, side portions 2 and 4 are used as ailerons exactly as with conventional airplanes.

I claim:

1. A circular wing having a streamline contoured major front portion and a streamline conthe trailingedge of the front portion.

3. A circular wing having a streamline contoured major front portion and a streamline contoured falcate minor rear portion, said rear portion being in spaced relation to said front portion so that the leading edge of the rear portion is positioned substantially below the trailing edge oi.' the front portion.

4. A circula wing comprising a major streamline contoure front portion, a minor streamline contoured ap'portion behind the central region of said iront portion, t'wo streamline contoured aileron portionsbehind the two side regions respectively of said front portionfthe trailing edge of said front portion being substantially alike to the composite leading edge of said ap and aileron portions forming an arc open to the front, said leading edges of the iiap and aileron portions being positioned -below and in spaced relation to the trailing edge of the front portion, and means for turning the flap about a transverse axis so as to bring its leading edge into bodily contact with the trailing edge of the front portion.

5. A circular wing having a streamline contoured major front portion and a crescent streamline contoured minor rear portion in spaced relation thereto so that the leading edge of the rear portion is positioned substantially below the trailing edge of the front portion.

6. A circular wing having a streamline contoured major front portion and a crescent streamline contoured minor rear portion about one third in area of the front portion and being in spaced relation thereto so that the leading edge of the rear portion is positioned substantially below the trailing edge of the front portion.

STEFFEN P. NEMETH. 

